In a small saucepan, combine blueberries, granulated sugar, and lemon juice. Cook over medium heat, stirring occasionally, until blueberries burst and the mixture thickens slightly, about 5-7 minutes.

In a small bowl, whisk together cornstarch and water (if using) until smooth. Pour into the simmering blueberry mixture, stirring constantly, and cook for another 1-2 minutes until thickened.

Remove from heat and let cool completely. The compote will thicken further as it cools.

In a medium mixing bowl, whisk together Greek yogurt, softened cream cheese (if using), maple syrup, vanilla extract, and a pinch of salt until smooth and well combined.

Line a 12-cup muffin tin with paper liners.

Spoon about 2 tablespoons of the yogurt mixture into the bottom of each muffin liner, spreading it evenly.

Add about 1 teaspoon of the cooled blueberry compote on top of the yogurt layer.

Using a skewer, toothpick, or the back of a small spoon, gently swirl the blueberry compote into the yogurt mixture to create a marbled effect.

Repeat for all 12 liners, then top each with another 1-2 tablespoons of yogurt mixture, gently spreading it to cover most of the compote, leaving some visible for the swirl effect. Add another small dollop of compote and swirl again if desired for a more pronounced swirl.

Place the muffin tin in the freezer for at least 3 hours, or until the bites are completely firm.

Once frozen, carefully remove the yogurt bites from the muffin liners. They can be stored in an airtight container.